1. Field of the Invention
The present invention relates to a corneal surgical apparatus for incising the cornea of an eye of a patient in a layered format the time of a keratorefractive surgery or the like.
2. Description of the Related Art
In recent years, attention has been focused on LASIK (laser in situ keratomileusis) surgery for effecting keratorefractive treatment wherein after a flap is formed by incising a corneal portion with a thickness of 150 xcexcm ranging from the corneal epithelium to the corneal stroma with one end of the cornea remaining connected like a hinge, the corneal stroma is cut away or ablated in a refractive correction amount by excimer laser light, and the flap is then returned to its original position. In this LASIK surgery, a corneal surgical apparatus called a microkeratome is used to incise the cornea in a layered form.
A typical microkeratome includes a suction ring having an opening, which is to be vacuum-fixed to a part of the cornea ranging from a corneal ring portion to the surface of the conjunctiva, a cornea applanating member for flatly applanating the cornea projected from the opening, and a blade moved in the direction toward the hinge while being oscillated in the lateral direction so as to incise the flattened cornea into a layered form with a substantially uniform thickness.
Since the corneal curvature of the patient""s eye differs depending on individuals, a height of the cornea projected from the opening of the suction ring vacuum-fixed differs, and thus the diameter of the flap formed as a consequence of the corneal incision also differs. That is, as the height of the projected cornea is larger, the diameter of the formed flap is larger. For this reason, plural kinds of suction rings having respective, different opening diameters must be preliminarily prepared, so that an appropriate one of the suction rings is selected depending on the corneal curvature of the patient""s eye to make the height of the projected cornea uniform and to form the flap having the uniform diameter. Alternatively, such a device has been proposed that, as shown in FIGS. 11(a) and 11(b), the height of the suction ring (an outer suction ring) can be adjusted to make the height of the cornea projecting from the opening uniform, thereby forming the flap having the uniform diameter.
The above-noted procedures can be used in a case where the diameter of a flap is changed. That is, if the diameter of the flap should be made large or small, an appropriate one is selected from plural suction rings having respective, different opening diameters or the height of the suction ring is adjusted, thereby changing the height of the cornea projected from the opening.
The provision of the plural kinds of the suction rings increases the cost, and the interchange of the suction rings depending on the patient""s eye requires troublesome work. The height adjustment of the suction ring requires, particularly, an unskilled operator, to take time, resulting in an extra load on the patient.
In view of the above-described problems, it is an object of the present invention to provide a corneal surgical apparatus, which is simple in structure and which is capable of forming a flap having a uniform diameter regardless of the differences in corneal curvature.
Another object of the present invention is to provide a corneal surgical apparatus, which can easily change the flap diameter.
To achieve the above-noted objects, the present invention is characterized by the following features.
(1) A corneal surgical apparatus for incising a cornea of a patient""s eye in a layered form, comprising:
a suction ring having an opening, which is vacuum-fixed to the patient""s eye so that the cornea is projected from the opening;
incising means, having a blade and an applanating member, for incising the cornea projected from the opening using the blade while applanating the cornea using the applanating member; and
height changing means for changing a height of a tip of the blade in a visual axis direction of the patient""s eye with respect to the suction ring.
(2) The apparatus of (1), wherein the incising means includes a shaft for linearly moving the blade in an incise direction, and the height changing means includes tilting means for tilting the shaft in the visual axis direction.
(3) The apparatus of (2), wherein the tilting means includes a fulcrum member about which the shaft is inclined.
(4) The apparatus of (1), wherein the incising means includes a shaft for linearly moving the blade in an incise direction, and the height changing means includes moving means for translating the shaft parallelly in the visual axis direction.
(5) The apparatus of (4), wherein the moving means includes a guide member for guiding parallel translation of the shaft.
(6) The apparatus of (1), wherein the incise means includes a shaft for linearly moving the blade in an incise direction, first driving means for moving the shaft forwardly, second driving means for rotating the shaft, and transmitting means for converting rotation of the shaft into lateral oscillations and transmitting the lateral oscillations to the blade.
(7) The apparatus of (1), further comprising:
informing means for providing information concerning the height of the tip of the blade in the visual axis direction, changed by the height changing means.
(8) A corneal surgical apparatus comprising:
a main body;
a suction ring fixedly provided on the main body, the suction ring having an opening;
a cutting unit movable substantially along a plane of the opening;
a drive unit supporting the cutting unit;
a support movably supporting the drive unit to the main body, and holding, through the drive unit, the cutting unit at a variable position in a direction substantially perpendicular to the plane of the opening.
(9) The apparatus of (8), wherein the support includes a fulcrum member about which the drive unit is pivotable, and a threading member rotatably held by the main body and threadingly engaged with the drive unit.
(10) The apparatus of (8), wherein the support includes a guide rail movably supporting the drive unit, a rack member provided to the drive unit, and a pinion member rotatably held by the main body and meshed with the rack member.
The present disclosure relates to the subject matter contained in Japanese patent application No. Hei. 11-280373 (filed on Sep. 30, 1999), which is expressly incorporated herein by reference in their entireties.